If you hold the mouse click, the tongue stays out. I’m not sure what the events are in Unity but i think an onmousedown event would work better in case of a slow click, instead of onmouseup.
It seems that you don’t need to aim the tongue, just click on the correct sprite. If you continue this or do something similar, may i recommend having the tongue go where the click was and then testing the end of the tongue on a sprite to see if they got it.
Cute game though.